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Modeling of Fuel Elements Cycling System in pebble Bed Reactor Based on Timed Places Control Petri Nets

Energy and Power Engineering 2013年第4期5卷 510-516页

作者： Hongbing Liu Peng Shen Dong Du Xin Wang Haiquan Zhang Department of Mechanical Engineering Tsinghua University Beijing China Institute of Nuclear and New Energy Technology Tsinghua University Beijing China

pebble bed reactors use cycling scheme of spherical fuel elements relying on fuel elements cycling system (FECS). The structure and control logic of FECS are very complex. Each control link has strict requirements on time and sequence. This increases the difficulties of description and analysis. In this paper, timed places control Petri nets (TPCPN) is applied for the modeling of FECS. On this basis the simulation of two important processes, namely uploading fuel elements into the core for the first time and emptying the core is finished by simulation software Arena. The results show that as TPCPN is able to describe different kinds of logic relationship and has time properties and control properties, it’s very suitable for the modeling and analysis of FECS.

关键词： Timed Places Control Petri nets (TPCPN) Arena pebble Bed Reactors Fuel Elements Cycling System (FECS)

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Study of heat transfer by using DEM–CFD method in a randomly packed pebble-bed reactor

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Nuclear Science and Techniques 2019年第2期30卷 123-134页

作者： Qiang Niu Na-Xiu Wang Shanghai Institute of Applied Physics Chinese Academy of Sciences CAS Innovative Academies in TMSR Energy System Chinese Academy of Sciences University of Chinese Academy of Sciences

The pebble-bed reactor is one of the most promising designs for the nuclear energy industry. In this paper,a discrete element method-computational fluid dynamics(DEM-CFD) approach that includes thermal conduction, radiation, and natural convection mechanisms was proposed to simulate the thermal-fluid phenomena after the failure of forced circulation cooling system in a pebble-bed core. The whole large-scale packed bed was created using the DEM technique, and the calculated radial porosity of the bed was validated with empirical correlations reported by researchers. To reduce computational costs, a segment of the bed was extracted, which served as a good representative of the large-scale packed bed for CFD calculation. The temperature distributions simulated with two different fluids in this DEM-CFD approach were in good agreement with SANA experimental data. The influence of the natural convection mechanism on heat transfer must be taken into account for coolants with strong convective capacity. The proposed DEM-CFD methodology offers a computationally efficient and widely applied method for understanding the heat transfer process in a pebble-bed core. The method can also be easily extended to assess the passive safety features of newly designed fluoride-salt-cooled pebble-bed reactors.

关键词： Discrete element method Computational fluid dynamics pebble bed Heat transfer Natural convection

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EVOLUTION　OF　RAPIDS　OF　CREEK　MOUTH－BAR　AT　GEZHOUBA　RESERVOIR　AND　THE　IMPACTS　ON　NAVIGABLE　CHANNEL　IN　THE　UPPER　REACHES　OF　THE　CHANGJIANG　RIVER

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Chinese Geographical Science 1996年第3期6卷 223-230页

作者：林承坤高锡珍 Department of Geo-and Ocean Sciences Nanjing University Nanjing PRC

ＥＶＯＬＵＴＩＯＮＯＦＲＡＰＩＤＳＯＦＣＲＥＥＫＭＯＵＴＨ－ＢＡＲＡＴＧＥＺＨＯＵＢＡＲＥＳＥＲＶＯＩＲＡＮＤＴＨＥＩＭＰＡＣＴＳＯＮＮＡＶＩＧＡＢＬＥＣＨＡＮＮＥＬＩＮＴＨＥＵＰＰＥＲＲＥＡＣＨＥＳＯＦＴＨＥＣＨＡ... 详细信息

ＥＶＯＬＵＴＩＯＮＯＦＲＡＰＩＤＳＯＦＣＲＥＥＫＭＯＵＴＨ－ＢＡＲＡＴＧＥＺＨＯＵＢＡＲＥＳＥＲＶＯＩＲＡＮＤＴＨＥＩＭＰＡＣＴＳＯＮＮＡＶＩＧＡＢＬＥＣＨＡＮＮＥＬＩＮＴＨＥＵＰＰＥＲＲＥＡＣＨＥＳＯＦＴＨＥＣＨＡＮＧＪＩＡＮＧＲＩＶＥＲ￥ＬｉｎＣ...

关键词： Gezhouba Reservoir pebble bed load rapids of creek mouth--bar navigable channels

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量子点/纳米水凝胶荧光探针的制备及其应用研究

量子点/纳米水凝胶荧光探针的制备及其应用研究

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作者：李颢东南大学

学位级别：硕士

量子点(Quantum dots,QDs),又称纳米晶,具有独特的物理化学性质,如高亮度、高抗光漂白性、宽吸收窄发射、易于能量/电荷转移及表面功能化修饰等,已发展成为一类代表性的荧光探针,广泛应用于标记、传感、生物成像等领域。纳米水凝胶(Nano... 详细信息

量子点(Quantum dots,QDs),又称纳米晶,具有独特的物理化学性质,如高亮度、高抗光漂白性、宽吸收窄发射、易于能量/电荷转移及表面功能化修饰等,已发展成为一类代表性的荧光探针,广泛应用于标记、传感、生物成像等领域。纳米水凝胶(Nanogel,NG)是纳米尺寸上由聚合物通过物理或化学方式交联而成的三维网状结构,具有含水量高、结构可调、抗污性强、靶标富集等特性。把各种荧光探针包覆于纳米水凝胶中构筑的pebble探针具有生物相容性好、稳定性高、检测灵敏等优点,特别适用于复杂生物环境下的传感、成像等应用。本论文首先基于量子点胶束(QM)修饰高密度核酸制备了多色球形核酸探针(QM-SNA),进一步将QM-SNA探针包覆于核壳结构的纳米水凝胶中构筑了QM-SNA@NG pebble探针。利用DNA酶步行器介导的信号放大技术,该新型pebble探针实现了活细胞内mi RNA原位、高分辨、多元的荧光成像分析。论文的主要研究结果如下:1.多色QM-SNA探针的可控制备。绿、黄、红三色油溶量子点分别通过薄膜水化法制得水溶性QM,进一步通过EDC/NHS缩合反应将金属离子依赖的DNA酶及猝灭剂修饰的底物序列偶联至QM表面制得QM-SNA。通过红外光谱、TEM、荧光光谱等手段对其组成、结构和性质进行了表征,结果表明QM-SNA具有球形核酸结构,显示荧光猝灭性质。2.基于QM-SNA的逻辑门控制、DNA酶步行器介导的信号放大技术。该信号放大技术包括:靶标mi RNA与锌离子双输入的“AND”逻辑门控制器,DNA酶步行放大器,QM荧光输出,即在靶标mi RNA和锌离子存在条件下激活DNA酶活性,DNA酶识别剪切特异性位点,以此驱动该序列沿QM表面DNA轨道(底物序列)的自动化行走,导致猝灭剂释放和QM荧光信号恢复。凝胶电泳结果表明DNA酶行走确实由靶标mi RNA与锌离子组成的“AND”门控制。实时荧光测量实验确定QM上DNA酶行走的时间为40 min。3.QM-SNA@NG pebble探针的可控构筑和mi RNA检测。探针构筑分4步进行:St(?)ber法制备粒径为0 nm的二氧化硅球并表面氨基化;通过EDC/NHS反应在硅球表面偶联富含羧基的聚合物P(MVE-β-CD);QM-SNA表面接枝金刚烷(Ad),利用金刚烷与β-环糊精之间的主客体反应将QM-SNA组装至硅球表面;通过EDC/NHS反应使P(MVE-β-CD)与NH2-PEG-NH2分子相互交联原位合成水凝胶。TEM、水动力尺寸、Zeta电位测量以及稳定性、细胞毒性等实验表明,所制备pebble探针具有“硅核-水凝胶壳”结构、00 nm粒径、电中性以及良好的的物理化学稳定性和生物相容性。基于QM-SNA信号放大和NG的分析物富集效应,pebble探针可实现mi RNA的高灵敏、高特异性检测,检测限低至1 f M,线性范围为3.5个数量级。应用三色pebble探针,可实现缓冲液和粗血清样品中mi RNA的非标记、无扩增、多元检测。4.pebble探针用于活细胞内mi RNA原位、高分辨、多元荧光成像分析。荧光共定位实验表明,pebble探针可通过内吞作用进入细胞质,不进入细胞核。pebble探针可有效富集细胞内源性mi RNA和外源性锌离子,触发DNA酶步行器介导的信号放大,实现高分辨mi RNA荧光成像。应用三色pebble探针,可实现同一细胞内三种mi RNA(mi R-196a、mi R-25、mi R-21)的多通道成像。依不同细胞内三种mi RNA表达水平不同,基于pebble探针的荧光成像实现了肺上皮细胞与非小细胞肺癌细胞(NSCLC)的区分,并进一步实现了不同NSCLC亚型细胞的有效区分。

关键词：量子点胶束球形核酸纳米水凝胶 pebble DNA酶步行器 miRNA检测细胞成像

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